Power electronics devices are often utilized in high-power electrical applications, such as inverter systems for hybrid electric vehicles and electric vehicles. Power semiconductor devices such as power IGBTs and power transistors, for example, may be thermally coupled to an insulated metal substrate comprising a dielectric layer positioned between two metal layers. The insulated metal substrate may then be further thermally coupled to a cooling structure, such as a heat sink. During operation of power electronics devices, thermally-induced stresses occur within the packaged structure due to coefficient of thermal expansion (CTE) mismatch of the structure's component layers.
Operation of the power semiconductor devices may generate high thermal loads that may cause the layers of the insulated metal substrate to flex due to CTE mismatch, which could damage the insulated metal substrate and/or the power electronics device package. To alleviate thermally-induced stresses, a punched metal base plate has been used as an interface layer between the bottom layer of the insulated metal substrate and the cooling structure. The punched metal base plate has patterned through-holes positioned therethrough. The punched metal base plate helps to relieve stress on the insulated metal substrate during a brazed bond process (which may require a large amount of heat), as well as to relieve operational stresses caused by CTE mismatch under transient thermal conditions.
However, the addition of the punched metal base plate increases the cost of the overall power electronics assembly and also increases its size. Further, use of the punched metal base plate causes increased thermal resistance within the package. There exists a desire to reduce the cost and size of electrical components utilized in electrical systems while also optimizing thermal management.
Accordingly, a need exists for alternative power electronics assemblies, insulated metal substrates, and vehicles that optimize thermal performance.